The subject matter described herein relates to systems and methods for preparation of epitaxially grown textured thick films.
A thick film is particularly useful in solar cell applications because a thicker film can absorb more photons and thereby produce more electricity. A solar cell or photovoltaic cell is a device that converts light energy into electrical energy. A solar or photovoltaic cell generates electricity in a light absorbing material upon exposure of the material to light. When light energy strikes the solar cell, the photovoltaic effect produces electricity.
The light absorbing material is typically a semiconductor material. There are currently several different semiconducting materials used in solar cells and a common material is silicon. The most efficient form of silicon (e.g., to capture the greatest amount of energy from the incident light) is as a single crystal silicon. However, single-crystal silicon wafers are costly. In many photovoltaic applications, the silicon used is a relatively thick polycrystalline or amorphous silicon film. For example, a film having a thickness of about 1 μm to up to 20 μm can be used. Polycrystalline silicon or amorphous silicon can be used in an attempt to reduce manufacturing costs. However, the resulting cells are not as efficient as cells using single crystal silicon.
Silicon thin-films can be made through chemical vapor deposition (CVD) (for example plasma-enhanced (PE-CVD)) from, for example, silane gas and hydrogen gas. Depending on the deposition's parameters, this can yield amorphous silicon (a-Si) or polycrystalline silicon (poly-Si). The solar cells made from these materials tend to have lower energy conversion efficiency than bulk silicon, but are also less expensive to produce and they can be produced on large surfaces.